Magnetic bearings are well known in the art and it has been proposed to incorporate such bearings into many types of motors by including additional windings on the stator poles. Excitation of these bearing windings induces radial forces on the rotor which may be used to support the rotor in the absence of mechanical bearings.
The use of such bearing windings, while advantageous, increases the complexity and size of the motor. In such motors, the magnetic bearing windings are wound on the stator poles with the stator phase windings. In addition, the magnetic bearing windings and the stator phase windings must be controlled separately.
In switched reluctance machines, the stator poles are normally wound in series such that, for a three phase machine with twelve stator poles, each phase winding would consist of four series subwindings. The subwindings would be radially spaced around the stator at equal intervals. Since the introduction of separate magnetic bearing windings would increase the size of the motor and complicate manufacture of the switched reluctance machine, it would be advantageous to use the existing phase windings of a switched reluctance machine to create the magnetic forces necessary to support the rotor in the absence of a mechanical bearing.